Here's another thought: It's a piece in the opinion section. They publish a variety of people in the opinion section. Sometimes they publish Paul Krugman. Sometimes they publish Karl Rove or George W Bush (as ex-president). They do not present a unified ideological front.
That said, Rupert Murdoch has grandstanded in the past in rather transparently self-serving ways ("OMG google news is indexing my sites! but i don't want to make them stop, I want to make them keep doing it and pay me for the privilege somehow.")
Anyway. Usually Mr. Murdoch is perfectly willing to put his name to shamelessly self-serving saber-rattling and rent-seeking pieces (e.g. "omg BBC. british media is government controlled. please get rid of my competition.")
The article itself, FWIW, is basically a straw-man argument saying that anyone against SOPA is a bunch of dirty Commies who think it's a God-given right to pirate everything for free. If you'd like to read it (ew), Google the URL and click the resulting link. Or hack your Referer: or pretend you're Googlebot. I regret that I was only the second or third person on the comments page to say it was a load of BS and not the first.
Postscript (2): as user mapgrep pointed out below, the WSJ has a bad habit of labeling editorials 'Review and Outlook'. Meh.
There are two kinds of stories that normally appear in a newspaper's opinion section: bylined opinion pieces and editorials. The former are written by various people and should ideally represent a diverse range of viewpoints. But the latter are written by the paper's editorial board, and represent the paper's official stance. This appears to be the latter.
I bet if you actually counted the ratio of progressive vs corporatist editorials, the latter would be the overwhelming majority.
Let's not kid ourselves, the WSJ does have a pro-corporations agenda, it's owned by Rupert Murdoch; in Europe most people consider it a far-right paper. The Financial Times in comparison looks almost like a socialist rag.
That said, Rupert Murdoch has grandstanded in the past in rather transparently self-serving ways ("OMG google news is indexing my sites! but i don't want to make them stop, I want to make them keep doing it and pay me for the privilege somehow.")